If ubuntu runs slower than XP in VPC I'd call that very fishy.... Maybe Microsoft would make the argument that they can optimize VPC for windows b/c they know the code...but true virtualization on a dual core should be pretty much like native...

VMware has a free product and Parallels is like $50 for the windows version. I'm not suggesting that you need ubuntu badly enough to shell out $50 or anything. I think that you are probably right in that you won't get a whole lot out of ubuntu that you cannot do with vista (except the shell, which to me is invaluable )... but I'd be paranoid about why one OS runs faster than another, epically when ubuntu really should be smoking fast... on the other hand, surfing in ubuntu is considerably safer than XP and maybe marginally safer than Vista... so it does make a nice sandbox environment.